calcium

calcium

(Ca) [kal´se-um]

a chemical element, atomic number 20, atomic weight 40.08. (See Appendix 6.) Calcium is the most abundant mineral in the body. In combination with phosphorus it forms calcium phosphate, the dense, hard material of the bones and teeth. It is an important cation in intracellular and extracellular fluid and is essential to the normal clotting of blood, the maintenance of a normal heartbeat, and the initiation of neuromuscular and metabolic activities.

Within the body fluids calcium exists in three forms. Protein-bound calcium accounts for about 47 per cent of the calcium in plasma; most of it in this form is bound to albumin. Another 47 per cent of plasma calcium is ionized. About 6 per cent is complexed with phosphate, citrate, and other anions.

Ionized calcium is physiologically active. One of its most important physiological functions is control of the permeability of cell membranes. Parathyroid hormone, which causes transfer of exchangeable calcium from bone into the blood stream, maintains calcium homeostasis by preventing either calcium deficit or excess.

Hypercalcemia: This is when the level of serum calcium rises above normal; neuromuscular activity begins to diminish. Symptoms include lethargy, muscle weakness (which, as the level of calcium increases, can progress to depressed reflexes and hypotonic muscles), constipation, mental confusion, and coma. The heartbeat also slows, which potentiates the effects of digitalis.

Hypocalcemia: This is a serum level of calcium that is below normal; it is manifested by increased neuromuscular irritability. When there is a deficit of ionized calcium, the nerve cells become more permeable, allowing leakage of sodium and potassium from the cells. This produces excitation of the nerve fibers and triggers uncontrollable activity of the skeletal muscles. Hence, as the calcium level continues to drop, the patient begins to experience muscle twitching and cramping, grimacing, and carpopedal spasm, which can quickly progress to tetany, laryngospasm, convulsions, cardiac arrhythmias, and eventually to respiratory and cardiac arrest. Relatively early signs of hypocalcemia are a positive trousseau's sign and a positive chvostek's sign.

Dietary sources of calcium include dairy products (such as milk and cheese), soybeans, fortified orange juice, dark green leafy vegetables (such as mustard greens and broccoli), sardines, clams, and oysters. The recommended dietary allowance of calcium for children aged 4 to 8 is 800 mg, and that for women aged 50 to 70 is 1200 mg. (See tables in the Appendices for recommended dietary allowances across the life span.) It is difficult to meet these requirements without including milk or milk products in the daily diet. The most familiar calcium deficiency disease is rickets, in which the bones and teeth soften. However, it is believed that a large number of people suffer from subclinical calcium deficiency because of poor eating habits. Since calcium is essential to the formation and maintenance of strong bones, an adequate intake is important in the prevention of osteoporosis.

calcium acetate the calcium salt of acetic acid; administered orally as a source of calcium and as a phosphate binder, such as in patients with end-stage renal disease. Also used as a pharmaceutical buffering agent.

calcium carbonate an insoluble salt occurring naturally in bone, shells, and chalk; used as an antacid, calcium supplement, and phosphate binder, and for treatment of osteoporosis.

calcium channel blocker (calcium channel blocking agent) a drug such as nifedipine, diltiazem, or verapamil that selectively blocks the influx of calcium ions through a calcium channel of cardiac muscle and smooth muscle cells; used in the treatment of Prinzmetal's angina, chronic stable angina, and cardiac arrhythmias. Calcium channel blocking agents act to control arrhythmias by slowing the rate of sinoatrial node discharge and the conduction velocity through the atrioventricular node. They act in vasospastic angina to relax and prevent coronary artery spasm. The mechanism of action in classical angina is a lowering of myocardial oxygen utilization by dilating peripheral arteries and thereby reducing total peripheral resistance and the work of the heart.

Physiologic activity of calcium channel blockers. (Data from Hardman J. and Limbird L., editors: Goodman and Gilman's The Pharmacologic Basis of Therapeutics, 9th ed., New York, McGraw-Hill, 1996; and the National Institutes of Health: The Sixth Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure, NIH Pub. No. 98-4080, Washington, DC, GPO, 1998.) From Edmunds and Mayhew, 2000.

calcium chloride a salt used in solution to restore electrolyte balance, treat hypocalcemia, and act as a treatment adjunct in cardiac arrest and in magnesium poisoning.

calcium citrate a salt used as a calcium replenisher; also used in the treatment of hyperphosphatemia in renal osteodystrophy.

calcium glubionate a calcium replenisher, used as a nutritional supplement and for the treatment of hypocalcemia; administered orally.

calcium gluceptate a calcium salt administered intramuscularly or intravenously in the prevention and treatment of hypocalcemia and as an electrolyte replenisher.

calcium gluconate a calcium salt administered intravenously or orally in the treatment and prevention of hypercalcemia and as a nutritional supplement. It is also administered by injection as a treatment adjunct in cardiac arrest and in the treatment of hyperkalemia.

calcium hydroxide an astringent compound used topically in solution or lotions.

calcium lactate a calcium replenisher, administered orally in the treatment and prevention of hypocalcemia and as a nutritional supplement.

calcium oxalate a salt of oxalic acid, which in excess in the urine may lead to formation of oxalate urinary calculi.

calcium pantothenate a calcium salt of the dextrorotatory isomer of the B vitamin pantothenic acid; used as a nutritional supplement. It is also available as racemic calcium pantothenate, which is a mixture of the dextrorotatory and levorotatory isomeric forms.

calcium phosphate a salt containing calcium and the phosphate radical; dibasic and tribasic calcium phosphate are used as sources of calcium.

calcium pyrophosphate deposition disease an acute or chronic inflammatory arthropathy caused by deposition of crystals of calcium pyrophosphate dihydrate in the joints and synovial fluid and chondrocalcinosis. Clinically, it may resemble numerous other connective tissue diseases such as arthritis and gout, or it may be asymptomatic. Acute attacks are sometimes called pseudogout.

cal·ci·um (Ca),

, gen.

cal·'ci·i

(kal'sē-ŭm, -sē-ī),

A metallic bivalent element; atomic no. 20, atomic wt. 40.078, density 1.55, melting point 842°C. The oxide of calcium is an alkaline earth, CaO, quicklime, which on the addition of water becomes calcium hydrate, Ca(OH)2, slaked lime. For some organic calcium salts not listed below, see the name of the organic acid portion. Many calcium salts have crucial uses in metabolism and in medicine. Calcium salts are responsible for the radiopacity of bone, calcified cartilage, and arteriosclerotic plaques in arteries.

[Mod. L. fr. L. calx, lime]

calcium

/cal·ci·um/ (Ca) (kal´se-um) a chemical element, at. no. 20. Calcium phosphate salts form the dense hard material of teeth and bones. The calcium 2+ ion is involved in many physiologic processes. A normal blood calcium level is essential for normal function of the heart, nerves, and muscles. It is involved in blood coagulation (in which connection it is called coagulation factor IV ). Various calcium salts, including the acetate, carbonate, chloride, glubionate, gluceptate, gluconate, lactate, lactobionate, and phosphate salts, are used as calcium replenishers and supplements.

calcium carbonate an insoluble salt, CaCO3, occurring naturally in shells, limestone, and chalk and also used in more purified forms; used as an antacid and calcium replenisher and in the treatment of osteoporosis.

calcium chloride a salt, CaCl22H2O, used in the treatment of hypocalcemia, electrolyte depletion, and hyperkalemia, and as a treatment adjunct in cardiac arrest and in magnesium poisoning.

calcium citrate a calcium replenisher also used in the treatment of hyperphosphatemia in renal osteodystrophy.

calcium glubionate a calcium replenisher, used as a nutritional supplement and for the treatment of hypocalcemia.

calcium gluceptate a calcium salt used in the treatment and prophylaxis of hypocalcemia and as an electrolyte replenisher.

calcium gluconate a calcium salt used to treat or prevent hypercalcemia, nutritional deficiency, and hyperkalemia; also used as a treatment adjunct in cardiac arrest.

calcium hydroxide a salt, Ca(OH)2, used in solution as a topical astringent.

calcium oxalate a salt of oxalic acid, which in excess in the urine may lead to formation of oxalate calculi.

calcium sulfate the sulfate salt of calcium, CaSO4, occurring in the anhydrous form and in a hydrated form (gypsum, q.v.), which upon being calcined forms plaster of Paris.

calcium (Ca)

[kal′sē·əm]

Etymology: L, calx, lime

an alkaline earth metal element. Its atomic number is 20; its atomic mass is 40.08. Its metallic form is a white flammable solid, brittle and somewhat harder than lead. Calcium is commonly produced by the electrolysis or thermal dissociation of calcium chloride. Calcium carbonate is the most common calcium compound. Calcium also occurs as a component of the natural compound gypsum, which forms plaster of paris when heated. It is also a component of calcium cyanamid, a fertilizer and progenitor of other nitrogen compounds. Calcium is the fifth most abundant element in the human body and is mainly present in the bone. The body requires calcium ions for the transmission of nerve impulses, muscle contraction, blood coagulation, cardiac functions, and other processes. It is a component of extracellular fluid and of soft tissue cells. The average daily human intake of calcium varies from 200 to 2500 mg. In the United States, dairy products are the major dietary sources of this element. The daily dietary allowances recommended by the Food and Nutrition Board vary from 360 mg for infants to 1200 mg for women 15 to 18 years of age. More than 90% of the calcium in the body is stored in the skeleton, which constantly exchanges its supplies with the calcium of the interstitial fluids. The endocrine system controls the concentration of ionized calcium in the plasma. Only a fraction of this amount is ionized and diffusible; the rest is bound to proteins, especially albumin. It is the ionized, diffusible portion of calcium that participates in the physiological changes associated with hypocalcemia. About one third of the calcium ingested by humans is absorbed, primarily in the small bowel. Vitamin D, calcitonin, and parathyroid hormone are essential in the metabolism of calcium. The degree of cell permeability varies inversely with calcium ion concentration. Abnormally high levels of ionized calcium in the extracellular fluid can produce muscle weakness, lethargy, and coma. A relatively small decrease from the normal level of this element can produce tetanic seizures. Normal adult blood levels of calcium are 9 to 10.5 mg/dL or 2.25 to 2.75 nmol/L.

calcium

A bivalent metallic element (atomic number 20; atomic weight 40.08) that is critical for bone and tooth formation and intimately linked to many metabolic processes, including muscle contraction, neural transmission, coagulation and inhibition of cell destruction. Calcium levels in the blood are controlled by the balanced action of parathyroid hormone and calcitonin. It is present in dairy products, almonds, leafy greens, sardines and salmon; proper absorption of calcium hinges on appropriate acidity of the stomach, presence of vitamin D and a balance of other minerals, including phosphorus and mangesium.

cal·ci·um

A metallic bivalent element; atomic no. 20, atomic wt. 40.078, density 1.55, melting point 842°C. Many calcium salts have crucial uses in metabolism and in medicine. Calcium salts are responsible for the radiopacity of bone, calcified cartilage, and arteriosclerotic plaques in arteries.

[Mod. L. fr. L. calx, lime]

calcium

(kal'se-um) [ calci- + -ium] Ca

A silver-white metallic chemical element, atomic number 20, atomic weight (mass) 40.08. Lime (calcium oxide), CaO, is its oxide. Calcium is a major component of limestone. Hydroxylapatite, a calcium phosphate, makes up about 75% of body ash and about 85% of mineral matter in bones.

Function

Calcium is important for blood clotting, enzyme activation, and acid-base balance. It gives firmness and rigidity to bones and teeth. It is essential for lactation, the function of nerves and muscles (including heart muscle), and maintenance of membrane permeability. Most absorption of calcium occurs in the duodenum and is dependent on the presence of calcitriol. Dietary factors affecting calcium absorption include phytic acid, consumption of too much phosphorus, and polyphenols found in tea. Approximately 40% of the calcium consumed is absorbed. Blood levels of calcium are regulated by parathyroid hormone; deficiency of this hormone produces hypocalcemia. The serum level of calcium is normally about 8.5 to 10.5 mg/dl. Low blood calcium causes tetany. Blood deprived of its calcium will not clot. Calcium is deposited in the bones but can be mobilized from them to keep the blood level constant when dietary intake is inadequate. At any given time, the body of an adult contains about 700 g of calcium phosphate; of this, 120 g is the element calcium. Adults should consume at least 1 g of calcium daily. Pregnant, lactating, and postmenopausal women should consume 1.2–1.5 g of calcium per day.

CAUTION!

calcium-45

45Ca

A radioactive isotope of calcium, half-life 164 days.

calcium chloride

CaCl2·2H2O, a salt used to raise the calcium content of the blood in disorders such as hypocalcemic tetany or overdose of calcium channel blocker or beta blocker. It is used in solution and administered intravenously. It is incompatible with epinephrine.

calcium glycerophosphate

calcium hydroxide

Ca(OH)2, a white powder used as an astringent applied to the skin and mucous membranes and in dentistry as cavity liner or a pulp-capping material under a layer of zinc phosphate. It induces tertiary dentin formation for bridging or root closure, but it may be related to a chronic pulpitis and pulp necrosis after pulp capping.

calcium saccharin

total serum calcium

calcium tungstate

CaWO4, a fluorescent material formerly used for radiologic imaging. It was used in intensifying screens to amplify the image, thereby reducing the radiation exposure to the patient.

calcium

A mineral present in large quantity in the body, mainly in the form of calcium phosphate in the bones and the teeth. Electrically charged calcium atoms (ions) are present in the blood and body fluids and are essential for many physiological processes including cell membrane permeability, cell excitability, the initiation and transmission of electrical impulses, muscle contraction, cell shape and cell motility. Calcium is necessary for blood coagulation, the production of ATP, and enzyme actions. Calcium levels in the blood are kept withing narrow limits by feedback mechanisms. Brand names of preparations containing calcium used to treat OSTEOPOROSIS are Ostram and Sandocal.

calcium (Ca)

an essential element to all animals and plants and a constituent of shells, bones and teeth.

Calcium

A silvery-yellow metal that is the basic element of lime and makes up about 3% of the earth's crust. It is the most abundant mineral in the human body. Calcium and phosphorous combine as calcium phosphate, the hard material of bones and teeth.

calcium

the most abundant mineral in the body. Combined with phosphorus in bones and teeth. The two together represent about 75% of the body's total mineral content. ionized calcium ( Ca2+), about 1% of the 1200 mg total calcium, plays a crucial role in all physiological functions including muscle action, blood clotting, transmission of nerve impulses, activation of several enzymes, synthesis of the active form of vitamin D, and transport across all cell membranes; its level in the blood is regulated by exchange with Ca in bone and by variation in renal excretion, under hormonal influences. Calcium is one of the most frequently inadequate nutrients in the diet of both athletes and non-athletes. Female dancers, gymnasts and endurance competitors are among those most prone to calcium dietary insufficiency. See also bone, coagulation, excitation-contraction coupling, hormones(tableTable 1), micronutrients, minerals, parathyroid gland, tetany.

calcium,

n an element/mineral that is essential for bone development and maintenance, nerve impulse conduction, and general cellular function. Calcium supplementation is useful for preventing osteoporosis and perhaps colon cancer. It is also used for treating PMS, colon polyps, and may be useful in lowering high blood pressure. Calcium supplements may interfere with the absorption of chromium, magnesium, manganese, iron, and zinc.

cal·ci·um

(Ca) (kal'sē-ŭm)

A metallic bivalent element; salts useful in metabolism and in medicine; responsible for radiopacity of bone, calcified cartilage, and arteriosclerotic arterial plaques in arteries.

[Mod. L. fr. L. calx, lime]

calcium (Ca) (kal´sēəm),

n a basic element, with an atomic weight of 40.07, found in nearly all organized tissues. Essential for mineralization of bone and teeth. The normal level of it in the blood is 9 to 11.5 mg/100 ml. A deficiency of it in the diet or in use may lead to rickets or osteoporosis. Overexcretion in hyperparathyroidism leads to osteoporotic manifestations. See also factor IV.

n a drug that inhibits the flow of calcium ions across the membranes of smooth muscle cells. The reduction of calcium flow relaxes smooth muscle tone and reduces the risk of muscle spasms. Calcium channel blockers are used in the prevention and treatment of coronary artery spasms.

calcium, dietary,

n the amount of absorbable calcium ingested daily.

calcium fluoride,

n a compound that is used as a flux in the manufacture of some silicate cements.

calcium hydroxide,

n a white powder that is mixed with water or another medium and used as a base material in cavity liners and for pulp capping.

calcium oxalate,

n an insoluble sediment in the urine and urinary calculi.

calcium phosphate,

n an odorless, tasteless white powder, the various forms of which are sometimes used as abrasives in dentifrices.

calcium salts,

n.pl the calcium present in salivary fluid as phosphates and carbonates. They are believed to form dental calculus on their precipitation from saliva.

n a chemical substance used in crystal form to coat screens; the screens fluoresce when struck by roentgen rays.

calcium

a chemical element, atomic number 20, atomic weight 40.08, symbol Ca. See Table 6. Calcium is the most abundant mineral in the body. In combination with phosphorus it forms calcium phosphate, the dense, hard material of the bones and teeth. It is an important cation in intra- and extracellular fluid and is essential to the normal clotting of blood, the maintenance of a normal heartbeat, and the initiation of neuromuscular and metabolic activities.

Within the body fluids calcium exists in three forms. Protein-bound calcium accounts for about 47% of the calcium in plasma; most of it in this form is bound to albumin. Another 47% of plasma calcium is ionized. About 6% is complexed with phosphate, citrate and other anions.

Ionized calcium is physiologically active. One of its most important physiological functions is control of the permeability of cell membranes. Parathyroid hormone, which causes transfer of exchangeable calcium from bone into the bloodstream, and calcitriol maintain calcium homeostasis by preventing either calcium deficit or excess.

calcium arsenate

used extensively as a spray in orchards, constituting a poison hazard for livestock.

an insoluble salt occurring naturally in bone, shells and chalk. A common form of supplementary calcium in dogs and cats on meat-based diets, used because of its high concentration of calcium (40%) and absence of phosphorus.

calcium challenge test

an intravenous infusion of calcium will cause increased levels of gastrin in dogs with a gastrinoma. Often used in combination with a secretin test.

a salt used in solution to restore electrolyte balance, to treat hypocalcemia and as an antidote to magnesium poisoning. Is highly irritant and has been discarded generally in favor of less irritating substances, e.g. calcium borogluconate.

calcium ethylenediamine tetra-acetic acid; the disodium and dipotassium salts are commonly used as anticoagulants in the preservation of blood samples for hematology. A chelating agent, used parenterally in the treatment of lead poisoning. See also edetate.

excess calcium

in all species may cause hypercalcitonism with decreased osteoclastic activity and skeletal remodeling. In dogs, disorders of enchondral ossification with curved radius and osteochondrosis have been demonstrated; secondary iron deficiency anemia occurs in piglets.

calcium fluoride

naturally occurring mineral. Called also fluorspar, fluorite.

calcium gel

contains high levels of calcium; given to cows as a drench or in the feed as a prophylaxis against milk fever.

an astringent compound used topically in solution or lotions; in dentistry used to encourage deposition of secondary dentine. Called also slaked lime. In solution, called lime water.

idiopathic calcium phosphate deposition

thought to be inherited as an autosomal dominant trait in Great Danes commencing in puppies about 5 weeks old, characterized by incoordination with deformity and displacement of the 7th cervical vertebra and mineral deposits in the intervertebral joints, in serous and synovial membranes and mineralization in most other tissues.

calcium lactate

used for supplementing the diet with calcium; contains 18% calcium. As calcium sodium lactate, containing 8% calcium, it is more soluble and can be used in drinking water.

calcium levulinate

a calcium compound used parenterally in the treatment of hypocalcemia; contains 14.8% calcium.

calcium mandelate

administered orally and used as a urinary antiseptic.

calcium nitrate

used as an additive during cheese making to control fermentation. Whey from this cheese may cause nitrate poisoning in pigs.

nondiffusible calcium

protein-bound fractions of plasma calcium.

calcium nutritional deficiency

nutritional deficiency of calcium is rarely primary except in carnivores on an all-meat diet. Secondary deficiency is usually the result of diets having too high a content of phosphorus. The outcome of either deficiency may be nutritional hyperparathyroidism, rickets, osteomalacia, osteodystrophy in horse and pigs, and degenerative arthropathy of cattle, depending on the species, age of the animal and availability of vitamin D. Hypocalcemia may not occur because of the activity of parathyroid hormone, but classical tetany and recumbency can occur if the deficiency is prolonged or if they are precipitated by some other factor.

calcium oxalate

a compound occurring in the urine in crystals and in certain calculi. See also oxalate urolith.

calcium oxide

alkaline and capable of causing gastroenteritis. There is a high concentration in basic slag and this may contribute to that poisoning.

calcium pantothenate

a calcium salt of the dextrorotatory isomer of pantothenic acid; used as a growth-promoting vitamin.

calcium phosphate

one of three salts containing calcium and the phosphate radical: dibasic and tribasic calcium phosphate are used as sources of calcium; monobasic calcium phosphate is used in fertilizer and as a calcium and phosphorus supplement. An important constituent of uroliths.

calcium : phosphorus ratio

the ratio of calcium to phosphorus in the diet, 1 : 1 to 1 : 2 is usually considered to be adequate for proper calcium nutritional status in most animal species. Diets outside this range are likely to cause osteodystrophies. Animals grazing phosphorus-deficient pasture, and those being intensively fed on grain rations which have an abnormally high phosphorus content, are the principal subjects. Horses on heavy grain diets and dogs and cats on meat diets without calcium supplementation are also targets for the disease.

calcium polycarbophil

a hydrophilic agent used as a bulk laxative in the treatment of constipation and diarrhea.

cards coated with calcium tungstate crystals are used to sandwich film in a light-tight cassette. They fluoresce when exposed to x-rays and, together with the beam, affect the film emulsion. They reduce the exposure factor required.

urinary calcium

calciuria.

Patient discussion about calcium

Q. It will be fine for my dad to take calcium as extra supplement; It will be fine for my dad to take calcium as extra supplement; as his bones are getting weak…. How much calcium intake is necessary for him?

A. Older men need more calcium, because, as they age, the body becomes less efficient at absorbing calcium and other nutrients. Intake amount can’t be judged without age and weight and other body conditions are known. Please don’t give supplements without doctor’s prescription as the chances of overdose are more problematic.

Q. My sister has been having major allergy problems.How could she get her desired calcium? My sister has been having major allergy problems. Now she has developed an allergy and cannot tolerate milk in any form. None of our family members had allergic reactions to milk and my sister very recently developed this symptom. Is there any possibility of this symptom linked with any other illness? How could she get her desired calcium intake required by the body? Can you make any suggestions please?

A. calcium is a very important part of our diet. lack of it will have a damaging effect. so it's good that you are aware!many good sources of calcium exist. These include seaweeds such as kelp, wakame . nuts and seeds (like almonds and sesame). blackstrap molasses, beans, oranges, figs, quinoa , broccoli...and another thing that you may do is crush an egg shell into powder and just mix a bit with her food. it's an excellent source.

Q. I'm concerned that my calcium supplements are contaminated w seashells or cow bones. Which brands are best

A. there should be labeled as "from animal source".here is something that helped me choose:http://www.mayoclinic.com/health/calcium-supplements/AN00964

In a recent paper, Choi, Yu, Lee, and Llin[sz]s announced that a specific calcium channel plays a crucial role in healthy sleep, a key step toward understanding both normal and abnormal waking brain functions.

The presentations discussed four major aspects of calcium channels that are relevant for understanding their roles in genetic and environmental neurologic disorders: the genetics and molecular biology of channel structure; interactions between calcium channels and intracellular signaling pathways; the effects of toxicants on calcium channel function, both through direct interactions with channel subunits and by altering intracellular signaling; and the genetics, molecular biology, and physiology of inherited disorders caused by mutations in the genes encoding calcium channel subunits or from autoimmune disorders caused by the generation of antibodies against subunits of those proteins.

In research published in this week's online edition of Science, postdoc Nicholas Vyleta and Professor Peter Jonas of the Institute of Science and Technology Austria (IST Austria) uncover the existence of loose coupling between calcium channels and release sensors of exocytosis at a mature central synapse in the rodent brain.

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